The present invention relates to radial diaphragm valves. More particularly, the invention is directed to a sanitary diaphragm valve that includes a dome shaped diaphragm and a bowl shaped valve cavity with various other features that provide a diaphragm valve that is easier to clean, has an extended cycle life, higher flow rates and that can operate at higher pressures.
Various fields such as, for example, biotechnology, semiconductor, pharmaceutical, food processing, and medical, require fluid handling systems that are clean and sterile while at the same time having increased cycle life and operating pressure. A very important consideration is ease with which the fluid handling components can be cleaned. The ease with which a system can be cleaned depends on, among other things, minimal dead volumes and entrapment areas. The fluid handling system must also use components that are inert to the fluid. Such systems often use valves as flow control devices, and diaphragm valves in particular are often used.
U.S. Pat. No. 5,549,134 (the xe2x80x9c""134 patentxe2x80x9d hereinafter), the entire disclosure of which is fully incorporated herein by reference, describes a diaphragm valve design that is particularly well suited for these various sanitary applications. The present invention is directed to various improvements and additional features in the design of the ""134 patent valve to enhance its cleanability and operating performance including, among other things, its operating pressure characteristic and cycle life. Still further the present invention is directed to increasing the flow rate.
To the accomplishment of the foregoing objectives, and in accordance with one embodiment of the invention, a sanitary diaphragm valve is provided that includes a dome shaped diaphragm having a central boss that can be connected to or driven by a valve actuator, an outer peripheral region, and a relatively thin web portion that connects the boss to the outer peripheral region. In one embodiment, the web portion is arcuate or dome shaped. The thinner web portion permits the diaphragm to have an extended cycle life and to enable the valve to operate at higher fluid pressures. In accordance with another aspect of the invention, the thin web may be defined by multiple curved surfaces. In one embodiment, the multiple curved surfaces are realized in the form of two surfaces with different radiuses of curvature.
In accordance with a further aspect of the invention, a valve body is provided that includes a bowl shaped valve cavity. This valve cavity includes an outer contour to permit more thorough cleaning and to eliminate entrapment areas. In a preferred embodiment, the valve cavity outer contour is realized in the form of a substantially vertical edge joined to the cavity by a smooth transition such as a radius, for example.
In a further embodiment of the invention, the actuator housing provides support surfaces for the diaphragm that reduces stress on the diaphragm particularly at higher operating pressures.
In accordance with another aspect of the invention, a deep bowl cavity design is used with a diaphragm that seals radially outside one of the valve ports. This concept greatly improves flow rates and also permits the port to open to the valve cavity off-axis to eliminate a right angle elbow inlet. Still a further aspect of the invention is a diaphragm stem that is undercut to provide a surface area that in response to back pressure urges the valve diaphragm to a closed position. This feature also may be used to realize a check valve.
These and other aspects and advantages of the present invention will be apparent to those skilled in the art from the following description of the preferred embodiments in view of the accompanying drawings.